Commit bdd5e75e4e2f30697f1635628d979af7a56e5f70
2013-12-03T06:57:02
[truetype] Fix phantom point handling. This is a further improvement to the changes from 2013-11-06. * src/truetype/ttgload.c (TT_Hint_Glyph): Horizontal phantom points are rounded horizontally, vertical ones are rounded vertically. (TT_LOADER_SET_PP): The horizontal position of vertical phantom points in pre-ClearType mode is zero, as shown in the OpenType specification.
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diff --git a/ChangeLog b/ChangeLog
index ca4699f..9ce39b6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2013-12-03 Werner Lemberg <wl@gnu.org>
+
+ [truetype] Fix phantom point handling.
+
+ This is a further improvement to the changes from 2013-11-06.
+
+ * src/truetype/ttgload.c (TT_Hint_Glyph): Horizontal phantom points
+ are rounded horizontally, vertical ones are rounded vertically.
+ (TT_LOADER_SET_PP): The horizontal position of vertical phantom
+ points in pre-ClearType mode is zero, as shown in the OpenType
+ specification.
+
2013-12-02 Werner Lemberg <wl@gnu.org>
[truetype] Fix change from 2013-11-20.
diff --git a/src/truetype/ttgload.c b/src/truetype/ttgload.c
index 90a5009..ca1f4b8 100644
--- a/src/truetype/ttgload.c
+++ b/src/truetype/ttgload.c
@@ -788,9 +788,13 @@
}
#endif
- /* round pp2 and pp4 */
+ /* round phantom points */
+ zone->cur[zone->n_points - 4].x =
+ FT_PIX_ROUND( zone->cur[zone->n_points - 4].x );
zone->cur[zone->n_points - 3].x =
FT_PIX_ROUND( zone->cur[zone->n_points - 3].x );
+ zone->cur[zone->n_points - 2].y =
+ FT_PIX_ROUND( zone->cur[zone->n_points - 2].y );
zone->cur[zone->n_points - 1].y =
FT_PIX_ROUND( zone->cur[zone->n_points - 1].y );
@@ -1282,8 +1286,11 @@
* specification defines the initial position of horizontal phantom points
* as
*
- * pp1 = (xmin - lsb, 0) ,
- * pp2 = (pp1 + aw, 0) .
+ * pp1 = (round(xmin - lsb), 0) ,
+ * pp2 = (round(pp1 + aw), 0) .
+ *
+ * Note that the rounding to the grid is not documented currently in the
+ * specification.
*
* However, the specification lacks the precise definition of vertical
* phantom points. Greg Hitchcock provided the following explanation.
@@ -1299,8 +1306,8 @@
*
* and the initial position of vertical phantom points is
*
- * pp3 = (x, ymax + tsb) ,
- * pp4 = (x, pp3 - ah) .
+ * pp3 = (x, round(ymax + tsb)) ,
+ * pp4 = (x, round(pp3 - ah)) .
*
* See below for value `x'.
*
@@ -1332,20 +1339,48 @@
* x = -DefaultDescender -
* ((DefaultAscender - DefaultDescender - aw) / 2) .
*
+ * For (old) non-ClearType hinting, `x' is set to zero.
+ *
*/
+#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING
+
#define TT_LOADER_SET_PP( loader ) \
do \
{ \
+ TT_Face face_ = (TT_Face)(loader)->face; \
+ TT_Driver driver_ = (TT_Driver)FT_FACE_DRIVER( face_ ); \
+ FT_Bool is_ver_38_ = (FT_Bool) \
+ ( driver_->interpreter_version == \
+ TT_INTERPRETER_VERSION_38 ); \
+ \
+ \
(loader)->pp1.x = (loader)->bbox.xMin - (loader)->left_bearing; \
(loader)->pp1.y = 0; \
(loader)->pp2.x = (loader)->pp1.x + (loader)->advance; \
(loader)->pp2.y = 0; \
- (loader)->pp3.x = (loader)->advance / 2; \
+ (loader)->pp3.x = is_ver_38_ ? (loader)->advance / 2 : 0; \
(loader)->pp3.y = (loader)->bbox.yMax + (loader)->top_bearing; \
- (loader)->pp4.x = (loader)->advance / 2; \
+ (loader)->pp4.x = is_ver_38_ ? (loader)->advance / 2 : 0; \
(loader)->pp4.y = (loader)->pp3.y - (loader)->vadvance; \
} while ( 0 )
+#else /* !TT_CONFIG_OPTION_SUBPIXEL_HINTING */
+
+#define TT_LOADER_SET_PP( loader ) \
+ do \
+ { \
+ (loader)->pp1.x = (loader)->bbox.xMin - (loader)->left_bearing; \
+ (loader)->pp1.y = 0; \
+ (loader)->pp2.x = (loader)->pp1.x + (loader)->advance; \
+ (loader)->pp2.y = 0; \
+ (loader)->pp3.x = 0; \
+ (loader)->pp3.y = (loader)->bbox.yMax + (loader)->top_bearing; \
+ (loader)->pp4.x = 0; \
+ (loader)->pp4.y = (loader)->pp3.y - (loader)->vadvance; \
+ } while ( 0 )
+
+#endif /* !TT_CONFIG_OPTION_SUBPIXEL_HINTING */
+
/*************************************************************************/
/* */